Common-mode moldable tube

Abstract

A co-moldable tube (10) is provided with: two rolling bearings (20) arranged along respective rotational axes (A); a spacer (40) interposed between the two rolling bearings (20) to impart structural rigidity to the co-mold formable tube (10); and a cylindrical housing sleeve (50) co-molded around the two rolling bearings (20) and the spacer (40); and two metal bushings (60) interposed between the cylindrical sleeve (50) and the two rolling bearings (20) so as to be co-molded with the cylindrical sleeve (50).

Description

Technical Field

[0001] The present invention relates to a co-mouldable tube.

[0002] The invention relates in particular to a tube co-mouldable with washing machine tubs, and the following description will refer explicitly to this tube without thereby losing its general character. Background Art

[0003] Tubes, which may be co-moulded with washing machine tubs, are designed to form an integral part of the tub to facilitate washing machine assembly operations and must support the rotating component of the tub, namely the drum.

[0004] Known types of tubes co-mouldable with washing machines generally include:

[0005] - two rolling bearings arranged along the axis of rotation of the washing machine drum;

[0006] - a spacer, interposed between the two rolling bearings and generally made of plastic material and having a box-like structure which gives rigidity to the tube structure; and

[0007] - A cylindrical containment sleeve made of plastic material and formed by co-moulding around the two bearings and the spacer.

[0008] In a co-mouldable tube of the type described above, two rolling bearings are mounted directly in opposite ends of a spacer and are also embedded inside the cylindrical containment sleeve. Furthermore, in addition to conferring structural rigidity to the sleeve, the spacer has the main function of, in particular, maintaining the two rolling bearings at a given axial distance from each other, these rolling bearings being provided with corresponding circumferential outer grooves which, during co-moulding of the sleeve, are filled with the same material as the sleeve so as to increase the axial and radial gripping between the sleeve and said rolling bearings. In other words, the two rolling bearings form an integral part of the cylindrical containment sleeve and in practice they cannot be maintained in the event of a failure of the rolling bearings, requiring, in the most critical case, replacement of the entire barrel, since it also forms an integral part of said co-mouldable tube.

[0009] Furthermore, the need to angularly stabilize the two rolling bearings relative to the cylindrical sleeve requires the provision of circumferential outer grooves, which result in additional production costs since they have to be machined in the steel of the rolling bearings. Summary of the invention

[0010] The object of the present invention is to provide a co-mouldable tube which, while retaining the advantages of known co-mouldable tubes (i.e. withstanding the ferrous oxides which may be formed due to the presence of water vapour and condensate which are normally present in most washing cycles), is in any case not subject to the above-mentioned disadvantages, i.e. allowing maintenance to be carried out in a quick and cost-effective manner as required.

[0011] According to the present invention, there is provided a co-mouldable tube having the characterising features set out in the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The invention will now be described with reference to the accompanying drawings, which show a non-limiting example of an embodiment of the invention, in which:

[0013] - Figure 1 is an axial cross-sectional view of a preferred embodiment of a co-moldable tube according to the present invention; and

[0014] - Figure 2 is based on Figure 1 A perspective view of a detail of a co-moldable tube. DETAILED DESCRIPTION

[0015] Referring to the accompanying drawings, 10 generally indicates a co-molded tube, preferably but not necessarily co-molded with a washing machine tub or any other fixed structural element, and if co-molded with the tub, the tube is designed to support a washing machine drum or any other part that rotates relative to the structural element.

[0016] For simplicity, the following description will refer specifically to the case where the tube 10 is co-moulded with a tub of a washing machine (shown schematically in the figures and indicated by 11) so as to define a single component with said tub 11 in a manner that reduces the production time of the washing machine.

[0017] The tube 10 comprises:

[0018] - two rolling bearings 20 arranged along the axis of rotation A of the washing machine drum (known and not shown);

[0019] a spacer 40 , axially interposed between the two rolling bearings 20 and made of a polymer material; and

[0020] A cylindrical containing sleeve 50 , preferably made of plastic material by co-molding around the two bearings 20 and the spacer 40 , also in order to optimize production time and costs.

[0021] Each rolling bearing 20 includes a corresponding inner ring 21 and a corresponding outer ring 22 , with a corresponding row of rolling elements (particularly balls) 23 interposed between the inner ring 21 and the outer ring 22 to allow the inner ring 21 to rotate relative to the corresponding outer ring 22 .

[0022] The spacer 40 is made of a plastic material, preferably but not necessarily, the spacer 40 is made of glass fiber reinforced polypropylene, and if both the sleeve 50 and the spacer 40 are made of the same plastic material, the process of co-molding the sleeve 50 on the spacer 40 can also intrinsically bond the surface portions (superficial portions) of the spacer 40 and the sleeve 50 together, making the overall structure of the tube 10 more rigid. According to an embodiment not shown here but easily inferred from what is described here, the spacer 40 can also be made of polybutylene terephthalate reinforced with glass fibers, or in any case made of a similar plastic material suitable for injection into a mold in a semi-liquid state to give the spacer 40, the structure of which will be described below.

[0023] The spacer 40 has a box-like structure and comprises an inner cylindrical body 41, a shaped outer body 42 coaxial with the body 41, and an intermediate radial partition wall 43, which is arranged in the transverse direction relative to the axis A and extends radially from the body 41 to the body 42 at a substantially middle position along the spacer 40 so that the body 41 is integral with the body 42. The body 41 and the body 42 together with the partition wall 43 define two annular spaces 44, so that the total weight of the spacer 40 is less than that of a solid spacer while ensuring the same rigidity characteristics. The spacer 40 also comprises a plurality of axial ribs 45, which are parallel to the axis A and arranged around the axis A inside the space 44, are made in one piece with the partition wall 43 and the body 41 and the body 42 and are made of the same material as the partition wall 43 and the body 41 and the body 42, and have correspondingly shaped outer axial profiles 451.

[0024] The shaped external body ( / external shaped body) 42 includes two axially opposite cylindrical end portions 421, which extend axially beyond the internal cylindrical body 41 and also beyond the outer axial profile 451 of the axial rib 45 to define corresponding cylindrical assembly seats 423 with the axial rib 45 or more precisely with the axial profile 451, the shape of the cylindrical assembly seats 423 being configured to be substantially flush with the cylindrical body 41 and axially inset relative to the opposite cylindrical end portions 421.

[0025] The co-mouldable tube 10 also comprises two metal bushings 60 interposed between the cylindrical sleeve 50 and the two rolling bearings 20 and co-moulded directly with said cylindrical sleeve 50. In particular, the bushings 60 are externally engaged (albeit partially) on the inside of the seat 423 of the spacer 40, co-moulded with the cylindrical sleeve 50 along the portion not engaged with the spacer 40, and provided with a respective internal assembly seat 61 for the respective rolling bearing 20: each seat 61 accommodates a respective bearing 20 on its inside, substantially separating the bearing 20 radially from the cylindrical sleeve 50, and since each assembly seat 61 remains axially open towards the outside of the tube 10 after the tube 10 has been co-moulded with the barrel 11, the respective bushing 60 allows the rolling bearing 20 to be extracted from said tube 10. In other words, the bushing 60 is directly interposed between the rolling bearing 20 and the cylindrical sleeve 50, preventing the sleeve 50 from being co-molded onto the rolling bearing 20, and the bushing 60 is also partially interposed between the rolling bearing 20 and the spacer 40, thereby allowing the rolling bearing 20 to be removed from the tube 10 even after the tube 10 is co-molded with the barrel 1.

[0026] Since the bushing 60 must ensure the assembly and positioning of the rolling bearing 20 in any case, that is, the bushing 60 must axially abut against the spacer 40 and be firmly fixed on the inner side of the sleeve 50, the bushing 60 includes corresponding clamping elements 62 located on the outside of the assembly seat 61 and connected to the sleeve 50, and corresponding axial engaging and locating elements 63 also located on the outside of the assembly seat 61 and connected to the corresponding opposite end 421 of the spacer 40.

[0027] According to the drawings and more particularly in Figure 2In the preferred embodiment of the tube 10 shown in FIG. 1 , the clamping element 62 comprises a plurality of axial outer grooves 621 and circumferential outer grooves 622 formed in axial intermediate positions between the axial outer grooves 621. The grooves 621 define corresponding radial teeth 623 between them and are completely filled with the plastic material of the sleeve 50 during the co-molding of the sleeve 50 with the assembly formed by the spacer 40, the bushing 60 and the bearing 20, thereby clamping the radial teeth 623 of the bushing 60 together to the sleeve 50 and producing a circumferentially secure connection of the bushing 60 to the sleeve 50. Furthermore, the circumferential outer groove 622, which essentially divides the axial outer groove 621 and the radial teeth 623 into two substantially similar parts, is completely filled with the plastic material of the sleeve 50 during co-molding of the sleeve 50 with the assembly formed by the spacer 40, the bushing 60 and the bearing 20, thereby forming radial teeth 51 in the sleeve 50 itself, which are inserted into the interior of the outer groove 622, thereby determining a firm connection between the bushing 60 and the sleeve 50 in the axial direction.

[0028] For each bushing 60, the axial engagement and positioning element 63 comprises a cylindrical flat surface 631 arranged laterally with respect to the corresponding axial outer groove 621, and an axial abutment shoulder 632 defined by said axial outer groove 621 or more precisely by the radial teeth 623. The cylindrical flat surface 631 radially engages on the inside of the axially opposite cylindrical end 421, while the axial shoulder 632 axially defined on one side of the corresponding cylindrical flat surface 631 is arranged to abut axially against the axially opposite cylindrical end 421, thereby obtaining a precise axial positioning of the two bushings 60 relative to each other. In particular, and for the sake of greater clarity, each cylindrical end 421 is radially delimited by a corresponding cylindrical surface 71 and by a corresponding annular end surface, the corresponding cylindrical surface 71 substantially defining a corresponding seat 423 for engaging with a flat surface 631 of the corresponding bushing 60, the corresponding annular end surface being transverse to the axis A and transverse to the surface 71 so as to axially abut against an axial shoulder 632 of the corresponding bushing 60: the axial distance between the two annular end surfaces 72 determines the axial distance for assembling the bushing 60 and the rolling bearing 20, the axial positioning of the rolling bearing 20 being further improved by the rib 45, as will be explained in more detail below.

[0029] The axial width of the bushing 60 is dimensioned equal to the axial width of the rolling bearing 20, and similarly the axial width of the seat 61 is dimensioned equal to the axial width of the outer ring 22, the outer ring 22 being integrally mounted (although in this way they cannot be uncoupled) on the inner side of the corresponding seat 61, the corresponding seat 61 being open axially on both sides: but if the opening towards the outside of the tube 10 allows the rolling bearing to be removed from the tube 10 as required (as already described), the opening towards the inside of the tube 10 allows the outer ring 22 to be positioned axially against the axial rib 45, the formed outer contour 451 of the axial rib 45 ensuring that while the outer ring 22 is effectively positioned against the rib 45, the inner ring 21 is instead axially spaced apart from the rib 45 to allow rotation relative to the inner ring 22.

[0030] Finally, for each metal bushing 60, the cylindrical containment sleeve 50 includes a corresponding radial containment edge 52, which is axially opposite to the corresponding cylindrical flat surface 631 with respect to the axial outer groove 621 and locks the corresponding metal bushing 60 axially against the surface 72 of the corresponding opposite end 421 of the spacer 40.

[0031] As is clear from the above description, the bushing 60 with which the co-mouldable tube according to the invention is provided allows a precise assembly of the rolling bearing 20 inside the spacer 40 and in particular allows the outer ring 22 of the rolling bearing 20 to be separated from the cylindrical housing sleeve 50, thereby avoiding the need to co-mould the cylindrical housing sleeve 50 directly onto the rolling bearing 20. In other words, the bushing 60 makes the rolling bearing 20 independent of the cylindrical housing sleeve 50 and allows a quick replacement of the rolling bearing 20 when necessary, also due to the axially open configuration of the inner seat 61 of the bushing.

[0032] Furthermore, although the bushing 60 is made of a metal material, like the inner ring 21 and the outer ring 22 of the rolling bearing 20, forming the clamping element 62 and the axial engagement and positioning element 63 on the bushing 60 can be performed in an undoubtedly more economical manner and with reduced cost, thereby making the use of additional structural elements (such as specifically the bushing 60 connected to the rolling bearing 20 and the spacer 40) absolutely competitive.

[0033] Finally, the grooves 621 and the associated teeth 623 can be formed in a specifically selected number depending on the type of application of the co-molded tube 10, and similarly, the circumferential outer grooves 622 can be formed to have a specific axial width and an axial position on the inner side of the grooves 621 and the associated teeth 623, again depending on the type of application of the co-molded tube 10, so that not only the type of rolling bearing 20 used can be selected substantially freely, but also the choice is certainly wider.

[0034] It will be understood that the invention is not limited to the embodiment described and illustrated here, which will be considered as an example of an embodiment of a co-mouldable tube 10, which can instead be further modified in terms of the form and configuration of the parts, the construction details and the assembly. In fact, as has been reiterated several times, the tube 10 is not only suitable for applications not strictly linked to washing machines and the associated tubs, but can also be used advantageously in other applications in which, for reasons of greater simplicity of production, the tube 10 must be co-moulded with a fixed support and must support parts that rotate relative to the fixed support, all while always ensuring sufficient rigidity characteristics and sealing capabilities against atmospheric agents (such as moisture, water vapour, etc.), and also facilitating maintenance and in any case with low production costs.

Claims

1. A co-moldable tube (10), comprising: - two rolling bearings (20), arranged along respective axes of rotation (A); - a spacer (40) interposed between the two rolling bearings (20) to provide structural rigidity to the co-mouldable tube (10); and - a cylindrical receiving sleeve (50) co-molded around the two rolling bearings (20) and the spacer (40); The co-moldable tube (10) is characterized in that the co-moldable tube (10) comprises two metal bushings (60), which are interposed between the cylindrical sleeve (50) and the two rolling bearings (20) and are co-molded with the cylindrical sleeve (50).

2. The co-moldable tube according to claim 1, characterized in that The two metal bushings (60) comprise a respective assembly seat (61) for each associated rolling bearing (20) and engage in respective opposite ends (421) of the spacer.

3. The co-moldable tube according to claim 2, characterized in that The two metal bushings (60) include axial engagement and positioning parts (63) which are located outside the assembly seat (61) and are coupled to the corresponding opposite ends (421) of the spacer (40).

4. The co-moldable tube according to claim 3, characterized in that The two metal bushings (60) include a clamping part (62) which is located outside the assembly seat (61) and is coupled to the cylindrical sleeve (50).

5. The co-moldable tube according to claim 4, characterized in that The clamping member (62) includes a plurality of axial outer grooves (621) and a circumferential outer groove (622) formed between the axial outer grooves (621).

6. The co-moldable tube according to claim 5, characterized in that The axial engagement and positioning component (63) includes a cylindrical flat surface (631) and an axial abutment shoulder (632), wherein the cylindrical flat surface (631) is laterally configured relative to the axial outer groove (621) and engages on the inner side of the corresponding opposite end (421) of the spacer (40), and the axial abutment shoulder (632) is also defined by the axial outer groove (621) and is installed axially against the corresponding opposite end (421) of the spacer (40).

7. The co-moldable tube according to claim 6, characterized in that The cylindrical receiving sleeve (50) includes a corresponding receiving edge (52) for each metal bushing (60), and the receiving edge (52) is positioned axially opposite to the corresponding cylindrical flat surface (631) with respect to the axial outer groove (621) and axially locks the corresponding metal bushing (60) against the corresponding opposite end (421) of the spacer.

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